1. Field of the Invention
The present invention relates to a liquid-phase epitaxial growth method of an inorganic compound consisting of a IIIb group element(s) and a Vb group element(s) of the Periodic Table (hereinafter referred to as a III-V group compound). More particularly, the present invention relates to a doping method of tellurium (Te) in the liquid-phase epitaxial growth method of a III-V group compound.
2. Description of the Related Art
Such III-V group compounds as GaAs, GaP, GaAs.sub.1-x P.sub.x, Ga.sub.1-x Al.sub.x As, and the like are used for the production of semiconductor elements, such as a light-emitting diode, a semiconductor LASER, and an FET. These semiconductor elements, particularly the light-emitting diode and the semiconductor LASER, are produced by using an epitaxial wafer, in which a thin film of the above-mentioned III-V group compounds is formed on a single crystalline substrate by means of the liquid-phase epitaxial growth method. In order to form an n-type epitaxial layer, one of Te and other n-type impurities is used as a dopant.
Conventionally, Te doping is carried out during liquid-phase epitaxial growth by directly incorporating the element Te into the melt for epitaxial growth (c.f. for example J. Nishizawa et al. Journal of Applied Physics 54(1983).5.P2807). However, according to the conventional method of directly incorporating the element Te into the melt for epitaxial growth, it is difficult to control the doping amount of Te because Te floats on the Ga melt and thus vapourizes, and, further the dopants in a trace amount is difficult to measure. Thus, epitaxial wafers having a requisite concentration of the n-type carrier cannot be produced with a high reproducibility.